Oops
by heroherondaletotheresuce
Summary: Modern AU – Tessa is messing around with her new found warlock powers and William is curious as to watch she can do when she accidentally turns him into a 3 year old version of himself and she doesn't know how to turn him back. - Mostly Fluff, Romance and Humor. / WESSA R&R Disclaimer inside. Just wrote this tonight, hope you enjoy it. :)


One Shot – WESSA

Modern AU – Tessa is messing around with her new found warlock powers and William is curious as to watch she can do when she accidentally turns him into a 3 year old version of himself and she doesn't know how to turn him back. – Fluff and Romance.

Disclaimer: Cassandra Clare owns her characters, I just own my story. Though I did get the idea based of a post.

Hope you enjoy this lovely one-shot and sorry for any mistakes, just wanted to get it up tonight for those waiting to read it. Love you all. xox

"Please Tess, just one spell. Nothing more." William pleaded, nuzzling his head in her neck, causing goose bumps to sprout along her smooth skin. She sighed, knowing that he wouldn't give up and finally gave in, willing to perform only one spell for him. She'd been practising with Magnus as much as she could, but seeing as though he was travelling with Jem, visiting Shang Hai and attempting to sneak into Peru, it was a little bit hard on her own. William had seen her reading her warlock books and texts, trying to get some background knowledge and insight and asked her if she could do a spell.

He was quite interested in the way of Magic now that Tessa was discovered to have the magical ability in her confusing lineage. Mostly, he just thought she'd look really hot performing a spell, with her hair floating around her gracefully and her eyes lighting up with excitement as she practised enchantment after enchantment. Though he didn't tell her that, otherwise she'd be sure to stop practising around him.

"Fine, just one spell. But I'd rather not, I'm not very good at this yet." She admitted her arms around Williams's neck.

"Just one please, for me?" he pouted and she rolled her eyes, placing a quick kiss on his lips before pushing him away playfully.

"Only one." Tessa said smiling in his direction. She had decided that she'd do a simple summoning spell that would bring Church to their apartment from the Institute, only a few miles away. She started to mutter the spell, the words flowing out of her mouth fluently as the phrases fell from her lips. Everything was going well, until she suddenly felt this power growing in the base of her palms, she turned them up, only to be blinded with a glowing blue colour. Her eyes went wide and she looked over at William who panicked, and even though stopped saying the enchantment, the fire in her hands grew bigger and bigger and she screamed and William ran to her immediately, as soon as his hand came in contact with her shoulder, her eyes were consumed in white and there was a surge of magic, pushing William and Tessa both back til they fell to the ground. Luckily her head landed on the soft carpet, softening the blow. She couldn't understand what could have gone wrong, there was this other power that she couldn't control. Groggily she sat up, rubbing the bruise now forming on her forehead and looked over to find William.

"Will." She groaned, her grey eyes searching the area around her. Her vision was still slightly blurry but soon enough her eyes focused on a baby boy sitting on the floor, about a foot in front of her. Her initial reaction was to scream because well there was a baby sitting in front of her and this baby looked freakishly like William who was still missing. Then the pieces started to click in her head and she realised what had just happened.

"By the angel. William." She blurted out, sitting up and moving closer to the baby boy before her.

"Te-sth-a" he mumbled, clapping his hands, his blue eyes lighting up with joy when he saw her. She picked him up and stood up, hoisting William on her hip. She just turned her hot as hell 21 year old boyfriend into a cute little baby.

"Are you okay baby?" she asked softly, rubbing his cheek and he just nodded making grabby hands at her and she couldn't help but laugh. He was the most adorable three year old, wow he was going to kill her when she changed him back. She held onto him tight in fear of dropping him and grabbed her mobile phone sitting on the coffee table.

She dialled Magnus's number, it rang for a few minutes before going to his voicemail and she left a message.

"Magnus… Uh- so my Magic sort of went wrong and now I'm stuck with a baby. Please call me back as soon as you can." She rushed into the short time span of the voicemail, trying to get her words in whilst William's small fingers played with her hair. She put the phone down hoping he would call back soon with a solution. She then sat down on the couch, placing William in her lap, her hand placed on his sides. She looked at him, a frown on her face. How was she going to turn him back? He must have noticed this because his little hands tried to reach her forehead, pushing away the stress lines. "I wove wuu." He mumbled and she laughed as he giggled and kissed him on the cheek. He seemed to be tired, his blue eyes slowly dropping closed, she held him close, his head resting on her chest and she grabbed a throw rug on the side of the couch and draped it over William and herself.

Her phone vibrated and she picked it up answering the call.

"Magnus thank god."

"Hi, Tessa thanks for that vague voicemail. What do you mean you have a baby, because I'm sure that unless you were talking about the magic you and William do in the bedroom-" and he was cut off by Tessa's harsh whisper.

"Not like that. Ugh- I was trying to do that spell you taught me and bring church here, when there was this weird glowing fire coming out of my hands and when William touched my shoulder he turned into a three year old." Tessa huffed out as quietly as she could, trying not to wake baby William from his slumber.

"Oh dear. Go to page 89 of the book I gave you recently and recite the counteract spell. It should turn William back to his older self. If that still doesn't work, then call me back." Magnus said quickly, before static sounded through the other side of the phone and he was cut off. Bad reception in China she guessed. She picked up William, placing him on the couch by himself and she kneeled down so that she was in eye level with him.

"Will, wake up. Come on. I'm going to change you back… unless you like being a baby." She cooed trying to wake him up, softly stroking his gorgeous black hair.

"William… wake up, otherwise I'm going to have to give you a bubble bath with a duck. And we both know how much you hate ducks." She laughed; if he didn't wake up she wouldn't be able to change him back. Slowly the boy's eyes opened and there was a pout on his face, and she couldn't help but notice how it was so similar to the one she saw only this morning. She missed him, even though he was still here, it was so very much different. She took his tiny hands in her own and started to chant the spell on page 89 that she had taken out before waking him. She felt the magic surge through her and into William, she prayed that this worked.

Slowly prying her eyes open she noticed obviously that he wasn't a baby anymore, but well he wasn't exactly 21 either. He looked like he was around 16, the day she met him at the institute. She jumped at him, hugging him, she was so happy to see him older even though he wasn't himself completely. William laughed and hugged her back and she kissed him on the cheek, starting to apologise.

"I am so sorry, oh my I really didn't mean to change you into a baby." She apologised profusely, biting her lip.

"It's alright Tess." He whispered, taking her hand in his.

"Wow, you look so young." She commented on his appearance, his hair was actually quite long, the dark locks curling at the edges, but his face was still as handsome as ever. His voice was slightly lighter than it was at the age of 21, but I guess puberty does things.

"Are you saying that I was old?" he teased, looking down at his younger body. He did note that it felt quite weird, though not as weird as being a baby.

"No no, so the spell didn't exactly work out. You're still well not 21." She groaned, plopping on the couch next to him.

"Can you change me back?" William asked, and she scratched her head in confusion. If the counteract spell sort of worked, what would she need to do to make it work completely?

"I'm not sure. I'll have to call Magnus back." She mumbled leaning back against the couch and closing her eyes. Her head was reeling; too much energy was taken out of her performing two spells in one day. She'd only just been getting the hang of one a day, this was draining her so bad, she wondered how Magnus controlled his powers, but he was after all 800+ years, plenty of time to practice.

"It's alright, I can think of a lot of things we can do til then." William said, moving his lips to her neck leaving hot kisses up her neck and all the way to her jaw. She moaned in delight and felt him smirk against her skin, making her insides tingle. His lips came on hers once again, riding her mind of all thoughts magical. She kissed him back, but then realised that this was wrong on quite a few levels. She put her hands on his chest and pushed him back slightly, no matter how much she wanted to keep kissing him she couldn't.

"Will, we can't. You're 16. I'm 20… it' just feels wrong." She said, and then realised that it probably wasn't the smartest or most considerate thing to say to her boyfriend.

"Really, does this feel wrong?" he smirked, pulling her in for a mind blowing kiss, his lips moving passionately against hers before he pulled away. She moved away dazed and didn't bother answering him, it didn't feel wrong, nothing felt wrong with him, but it was a bit awkward seeing as though he was 16. She picked up her phone dialling Magnus again. She needed to change him back; she didn't think she'd be able to control herself, especially with him around.

"Magnus, it didn't work. It just made him older, around 16 and now I'm stuck with a really horny and hormonal teenager. Help." She said in the phone, receiving a glare from William sitting next to her, who was drawing circles into the bare skin of her arms.

"Lovely. The only other thing I can think of is to give him a bit of fairy dust, which should fix the problem. Do you still have your Christmas present from last year?" Magnus inquired.

"Um, yeah I do, it's in my room. Wait, that was fairy dust, I thought it was just sparkles." Tessa admitted, she really thought it was sparkles, or perhaps some sort of make-up.

"Yes, it is. Just get some, grind it up and sprinkle and William should be back to normal."

"Thank you." She said, hanging up the phone.

She turned her head to face William who was staring her down, biting his lip in an irresistible manner. She rolled her eyes at his tactics and grabbed him by his hand, dragging him into her bedroom and taking the fairy dust and into the kitchen.

"Just have to grind this up and you are all back to normal." She said, taking out a mortar and pestle and grinding up the rest of the fairy dust to produce a power, rather than chunks of sparkles. William just stood there patiently, leaning his head in his palms on the bench top. Soon Tessa sprinkled the fairy dust over Williams head and there was a bright light and moments later he was back to his normal self. She literally jumped him. Holding her arms around his neck tight, his large hands on her waist, holding her close.

"Sorry about everything today." She chuckled kissing him on the lips.

"It's alright, it was kind of fun actually." He laughed, running his fingers through her hair.

"I think we have some unfinished business to attend to, don't you?" his voice husky and deeper than it was not more than 10 minutes ago and she loved it. She was so glad to have everything back to normal. Her grey eyes flew over his face, looking at every detail, noticing all the things that were missing before, like the darker blue in his eyes and the slight hint of stubble on his illegally superb jaw line.

"Mmm, I do believe so." She giggled as they walked off hand in hand to their bedroom, but they didn't even make it there because William had already pushed Tessa up against the wall of their living room, kiss her feverously with his arms around her waist and hers on his chest. She decided then that maybe it wasn't such a bad day after all.


End file.
